"""Light platform for Ninlight bulbs."""

from __future__ import annotations

import logging
from typing import Any

from homeassistant.components.light import (
    ATTR_BRIGHTNESS,
    ATTR_COLOR_TEMP_KELVIN,
    ATTR_RGB_COLOR,
    ATTR_TRANSITION,
    ColorMode,
    LightEntity,
    LightEntityFeature,
)
from homeassistant.core import HomeAssistant
from homeassistant.exceptions import HomeAssistantError
from homeassistant.helpers.entity_platform import AddEntitiesCallback

from .client import NinlightBadRequest, NinlightError, NinlightState
from .const import MAX_TRANSITION_MS
from .coordinator import NinlightConfigEntry, NinlightCoordinator
from .entity import NinlightEntity

_LOGGER = logging.getLogger(__name__)


async def async_setup_entry(
    hass: HomeAssistant,
    entry: NinlightConfigEntry,
    async_add_entities: AddEntitiesCallback,
) -> None:
    """Set up the light for a Ninlight bulb config entry."""
    async_add_entities([NinlightLight(entry.runtime_data, entry)])


def _to_ha_brightness(pct: int) -> int:
    """Bulb brightness is 1..100; HA brightness is 0..255."""
    return max(1, min(255, round(pct * 255 / 100)))


def _to_bulb_brightness(level: int) -> int:
    """The bulb rejects brightness 0 and anything above 100 (invalid brightness)."""
    return max(1, min(100, round(level * 100 / 255)))


class NinlightLight(NinlightEntity, LightEntity):
    """A Klyqa bulb running the Ninlight firmware."""

    # No translation_key: with has_entity_name and a single entity per device, HA names the
    # light after the device, giving light.schreibtisch_links rather than ..._bulb.
    _attr_name = None

    def __init__(self, coordinator: NinlightCoordinator, entry: NinlightConfigEntry) -> None:
        super().__init__(coordinator, entry)
        self._attr_unique_id = f"{(entry.unique_id or '').lower()}-light"
        self._attr_supported_features = LightEntityFeature.TRANSITION

    # Capabilities come from the polled state, not from a one-time __init__ snapshot: an
    # entry set up while the bulb was powered off starts from defaults and must pick up
    # the real RGB/CT range as soon as the bulb answers again.
    @property
    def available(self) -> bool:
        # An unreachable (powered-off) bulb is an expected state: the entity goes
        # unavailable instead of the config entry erroring.
        return self.coordinator.last_update_success and self.coordinator.data.available

    @property
    def supported_color_modes(self) -> set[ColorMode]:
        state = self.coordinator.data
        # Both modes for RGB bulbs: the firmware keeps the last color and the last color
        # temperature and picks between them with `mode`, exactly how HA models a
        # color_temp + rgb light.
        return {ColorMode.COLOR_TEMP, ColorMode.RGB} if state.has_rgb else {ColorMode.COLOR_TEMP}

    @property
    def min_color_temp_kelvin(self) -> int:
        return self.coordinator.data.ct_min

    @property
    def max_color_temp_kelvin(self) -> int:
        return self.coordinator.data.ct_max

    @property
    def is_on(self) -> bool:
        return self.coordinator.data.on

    @property
    def brightness(self) -> int | None:
        return _to_ha_brightness(self.coordinator.data.brightness)

    @property
    def color_mode(self) -> ColorMode:
        state = self.coordinator.data
        if not state.on:
            # Nothing is lit; reporting a mode would contradict is_on=False.
            return ColorMode.UNKNOWN
        if state.has_rgb and state.mode == "color":
            return ColorMode.RGB
        return ColorMode.COLOR_TEMP

    @property
    def color_temp_kelvin(self) -> int | None:
        state = self.coordinator.data
        return state.color_temp if self.color_mode == ColorMode.COLOR_TEMP else None

    @property
    def rgb_color(self) -> tuple[int, int, int] | None:
        state = self.coordinator.data
        if self.color_mode == ColorMode.RGB:
            return (state.r, state.g, state.b)
        return None

    async def async_turn_on(self, **kwargs: Any) -> None:
        state = self.coordinator.data
        payload: dict[str, Any] = {"on": True}

        if (level := kwargs.get(ATTR_BRIGHTNESS)) is not None:
            payload["brightness"] = _to_bulb_brightness(int(level))
        elif not state.on:
            # HA expects turn_on without a brightness to restore the previous level. The
            # firmware already does that (it keeps `brightness` while off), so sending it
            # would only re-assert a value the bulb may have clamped itself - but a bulb
            # that has never been on reports brightness 0, which its API rejects. Mirror
            # the last known value only when the bulb actually has one.
            if state.brightness < 1:
                payload["brightness"] = 100

        # The firmware rejects color and color_temp in one request with
        # "color and color_temp are exclusive", so pick one. HA only sends both when a
        # caller passes them together; color is the more specific intent and wins.
        kelvin = kwargs.get(ATTR_COLOR_TEMP_KELVIN)
        rgb = kwargs.get(ATTR_RGB_COLOR)
        seg: dict[str, Any] | None = None
        if rgb is not None and state.has_rgb:
            r, g, b = (int(max(0, min(255, v))) for v in rgb)
            if state.strip:
                seg = {"mode": "solid", "color": {"r": r, "g": g, "b": b}}
            else:
                payload["color"] = {"r": r, "g": g, "b": b}
        elif kelvin is not None:
            ct = max(state.ct_min, min(state.ct_max, int(kelvin)))
            if state.strip:
                seg = {"mode": "white", "color_temp": ct}
            else:
                payload["color_temp"] = ct

        if (transition := kwargs.get(ATTR_TRANSITION)) is not None:
            payload["transition"] = max(0, min(MAX_TRANSITION_MS, int(float(transition) * 1000)))

        await self._apply(payload, seg)

    async def async_turn_off(self, **kwargs: Any) -> None:
        payload: dict[str, Any] = {"on": False}
        if (transition := kwargs.get(ATTR_TRANSITION)) is not None:
            payload["transition"] = max(0, min(MAX_TRANSITION_MS, int(float(transition) * 1000)))
        await self._apply(payload, None)

    async def _apply(self, payload: dict[str, Any], seg_patch: dict[str, Any] | None) -> None:
        """Send one command and update immediately.

        POST /device/state answers with the full new state, so the coordinator does not
        need a refresh round-trip and the UI settles on the real bulb state at once.

        On the segment-model firmware the color goes into segment 0 as a separate PATCH
        (`PUT /device/segments/0`, fields omitted keep their value); the master on and
        brightness stay in the state POST, because the firmware's fade rides on them.
        Segment brightness stays untouched so master scaling remains the single knob.
        """
        try:
            data = await self.coordinator.client.set_state(payload)
            if seg_patch is not None:
                segs = self.coordinator.data.segments
                start = segs[0]["start"] if segs else 0
                end = segs[0]["end"] if segs else max(0, int(data.get("pixel_count", 1)) - 1)
                await self.coordinator.client.patch_segment(
                    0, {**seg_patch, "start": start, "end": end}
                )
        except NinlightBadRequest as err:
            # A rejected command is a bug or a firmware mismatch, not a network fault:
            # surface it to the caller and leave the entity's state alone.
            raise HomeAssistantError(str(err)) from err
        except NinlightError as err:
            self.coordinator.async_set_update_error(err)
            raise HomeAssistantError(str(err)) from err

        # Push the device's own reply through the coordinator so every entity of this
        # device (light, sensors) settles on the real state at once.
        segments = None
        if self.coordinator.data.strip:
            try:
                segments = (await self.coordinator.client.get_segments()).get("segments")
            except NinlightError:
                pass  # the next poll recovers it; the state reply above is still right
        self.coordinator.async_set_updated_data(
            NinlightState.from_api(data, self.coordinator.info, segments)
        )